In semiconductor manufacturing, process modules provide a surface for semiconductor wafer processing. Generally, there are two types of process modules: hot process modules and cold process modules. FIG. 1 illustrates hot process module 4 and cold process module 5. Hot process module 4 is used for heating wafer 7 while in an oven, and cold process module 5 is used for cooling wafer 7. A circular heating plate 6 resides in the center of hot process module 4. The plate radiates heat to maintain the temperature of wafer 7.
Processing a semiconductor wafer requires moving the wafer from one module to the next with as little physical contact as possible. Air flowing through perforations 3 in the process modules helps to keep wafer 7 from touching each process module surface. In addition, the two modules 4 and 5 are situated at a predetermined angle such that wafer 7 will be transferred from one module to the other at a given rate with minimal physical contact. This is called gravity wafer transport.
Gravity transport requires that the surfaces of the modules be aligned to reside in the same plane at all times. This alignment done during installation and periodically thereafter. Under one prior method of aligning process modules, a time-consuming trial and error approach is used to adjust the alignment of the two process modules so that they (1) are situated at a specific angle and (2) lie in the same plane. This prior method for adjusting the level and angle of process modules is discussed with reference to FIG. 1. Hot process module 4 is shown situated adjacent to cold process module 5. Test wafer 7 (supported by air flowing through air passages 3) is slid back and forth in directions 100 across process modules 4 and 5 while the process equipment is not operating. The level of modules 4 and 5 is adjusted using legs 2 until the modules are coplanar and at the proper transport angle. Generally, the angle of the two modules should be approximately one degree sloping from module 4 towards module 5. The angle is changed manually by eye by adjusting thumbscrews (or other leveling means) on legs 2 of modules 4 and 5.
If the modules are not coplanar, wafer 7 does not slide smoothly from one module to the adjacent module. When the wafer is slid back and forth in directions 100 and modules 4 and 5 are not coplanar, an audible "clicking" noise is generated. Legs 2 on modules 4 and 5 are adjusted by an operator until no "clicking" sound is heard. This helps to ensure that the two modules are coplanar. Coplanarity between the two modules allows the wafer to slide smoothly from one module to the next, thereby minimizing the likelihood of damage to the wafer.
Although this method of the prior art is generally effective, it is time-consuming and there is a relatively high likelihood of inaccurate adjustment. Improper alignment can result in damaged wafers as well as excessive equipment downtime for removal of particulates resulting from misaligned process modules. Particulates on process modules, damaged wafers, and excessive equipment down time all reduce wafer production.